The blue dot marks your spot at the Fernbank Museum of Natural History in Atlanta.

In an experiment with a mobile technology that has digital cartographers intrigued worldwide, the museum introduced a new "you are here" app feature this month that shows smartphone-toting visitors exactly where they are inside the museum.

If visitors opt in for the service, the app provides turn-by-turn directions to exhibits and delivers place-specific information about the objects near them.

Sounds of crickets and stomping noises from the app greet visitors who walk by the large Tyrannosaurus rex statute in the museum lobby. Puzzles, videos and IMAX trailers pop up throughout exhibits.

Using visitor traffic pattern data, the museum will determine the popular exhibits and where more internal advertising should go, says Jennifer Grant Warner, the museum's chief programming officer. "A lot of content and cool stuff are left on the cutting-room floor," she says. "Taking it to mobile devices gives a way to layer that information. I hope it convinces people to stay longer in the museum."

The museum also plans to add revenue-driving features in the future, including an alert for a free drink coupon when the café has fewer than 10 customers.

GPS is mostly useless indoors, so the the technology designers — a group that includes Cisco Systems, Qualcomm and indoor map developer Meridian — relied on Wi-Fi access points to detect the smartphones within their coverage area in the museum. The museum doubled the number of the Wi-Fi access points within the building to enhance accuracy.

Fernbank joins a growing number of institutions with lots of indoor space that are experimenting with the niche technology of indoor mapping. Because much of the outdoors — at least in the developed world — has been thoroughly mapped, digital cartographers view indoor space as an untapped but potentially lucrative field for delivering navigation, pushing out location-relevant information and promoting deals.

Facilities that can be challenging to navigate — hospitals, convention centers, universities, shopping malls, theme parks, sports stadiums, school systems, large office buildings and airports — are dabbling with tools offered by about 40 companies and start-ups that have indoor mapping products, according to a recent report by Gartner.

Though approaches vary widely, tapping Wi-Fi networks to triangulate a position, called Wi-Fi fingerprinting, seems to be the most widely pursued technology.

Some products, such as Meridian's map for The Venetian hotel in Las Vegas and the subway system in New York, don't need GPS or Wi-Fi signals but require users to specify their starting points and destinations for directions.

Other technologies, such as one from Nokia, propose maximizing the phone's Bluetooth capability by adding proprietary beacons or signal devices inside a building to capture location. The tools that reside in smartphones, such as the accelerometer, gyroscope, compass and step counters, also supply position information in relation to surrounding objects. Hyper-location detection gets better as these sensors get better, says Scott Pomerantz, general manager of GPS at Broadcom, which makes navigational tools for phone manufacturers.

Analysts caution that the technology is still immature, with high costs and accuracy issues keeping more prospective customers on the sidelines. Adding more Wi-Fi access points and other hardware is expensive. Most indoor positioning systems, even using Wi-Fi, still miss the precise location by several feet. And there aren't enough high-end smartphones in the market that can handle indoor positioning.

All companies in the market "have trade-offs in terms of accuracy," wrote Annette Zimmermann, an analyst at Gartner, in a recent report. Server connection, maintenance and the time it takes to deploy the technology also remain barriers, she says.

But the possibility of precisely tracking hordes of people as they move about indoors renders so many commercial opportunities that the technology could be — like GPS — "the foundational technology for a new ecosystem of businesses," says Dan Ryan, chief technology officer of ByteLight, a Boston start-up pursuing its own solution to indoor mapping using LED light bulbs. "The indoor map is going to be just as big."

Attesting to the potential, Google has pushed its software tools to businesses and institutions to make their own maps. The tech giant has collected 10,000 maps — including many U.S. airports, Ikea and the Smithsonian American Art Museum — that have been integrated into Google Maps. "Things are accelerating very quickly. This is the year when indoor maps became real," says Cedric Dupont, product manager of indoor maps for Google.

Microsoft's Bing Maps, which launched indoor maps in 2010, has 3,100 maps in 13 categories, including airports and stores.

Start-ups Wifarer, Micello, Meridian, Point Inside and MapEverywhere have also opened shop in recent years to grab their niche in the market. "We bet that every interesting building will have its own map," says Ankit Agarwal, CEO of Micello, a developer of software for making indoor maps.

Mapping out real-world applications

For some institutions, their foray into indoor maps is limited to a desire to create basic navigational tools. The public school district in Fort Lee, N.J., sent a photocopy of its blueprints for three schools to MapEverywhere. The map software firm converted them to detailed floor plans with critical infrastructure information and points of interest that can be accessed by firefighters' and first-responders' smartphones.

In January, Miami Children's Hospital plans to introduce a map on its app for patients traversing its maze of connected buildings.

But large retailers, with customers willing to spend money but often having trouble finding items, are the most eager adopters. Earlier this month, Macy's announced that shoppers of its Herald Square store in New York can download its app to find their position in the store — represented by a blue-dot — and receive turn-by-turn directions to departments and brands in the building. Meridian, which developed the map, claims "3 to 5 feet of accuracy."

While some may scoff at the notion of customers needing a map in a shop, about 20% of retail sales are lost because shoppers can't find items, estimates Nathan Pettyjohn, CEO of Aisle411, an app with 9,000 store maps.

Mobile apps are also becoming a key sales channel and are ideal tools for coupon distribution and bar code scanners. Adding a map on top of these features allows stores to target promotions more directly at relevant locations. Nudging customers to share what they buy also gives retailers valuable data for merchandising, inventory control and personalized deals.

"Maps are quickly becoming more valuable than a navigational tool. The underlying information has strong value for commerce," says of Nick Such, CEO of BuildingLayer, a tech firm that converts indoor floor plans to digital maps.

Walgreens partnered with Aisle411 to list store layouts in the Aisle411 app. Customers can make shopping lists, and the items are spotted on their store's map. Walgreens recently embedded the feature in its own app.

For Black Friday, Walmart expanded last year's program of distributing paper store maps by installing digital versions in its app. Meijer, a retail chain in the Midwest, also uses a mapping technology from Point Inside that shows the location of searched-for items on a map.

Working with local start-up Wifarer, the Royal BC Museum of Natural History in Victoria, Canada, introduced in August a feature in its app that pushes out relevant content about exhibits as phone owners stand in front of them. "It's about triggering content for events. That's a much bigger play than navigation," says Lise Murphy, vice president of marketing for Wifarer.

Fine-tuning accuracy issues

But accuracy remains a glaring problem for mapping technologies. "If you're looking for one of 40 restaurants in an area, that circle (the blue dot) has to be tight," says Paul Nash, principal group program manager of Bing Maps at Microsoft. "You'll find that, in the industry, the circle is still pretty large."

A group of indoor mappers is working to fine-tune indoor positioning, although the results are still preliminary and far from ready for a commercial market rollout.

At conventions this year, Nokia has demonstrated its project — high-accuracy indoor positioning (HAIP) — that would be able to determine a person's location within several inches. Prospective Nokia customers interested in the technology would have to install proprietary beacons in the ceiling or on walls that would detect the wandering smartphones by using a form of Bluetooth signals. Retailers monitoring shopper behavior, manufacturers tracking inventories and service companies with employees out in the field would be drawn to the technology, says Cliff Fox, Nokia's head of content business.

Nokia has launched seven undisclosed pilot tests, including at supermarkets, power plants and sports arenas. There will be several more added this year, Fox says.

CSR, a U.K.-based company, is also developing a Bluetooth-based technology with beacons that are installed in buildings or moving assets for tracking location.

ByteLight has also drawn investor interest with its unique approach of using existing LED bulbs as location detectors. LED bulbs, which are digital devices, can be calibrated to emit varied light strengths by making them switch on and off fast enough to be unnoticeable to the human eye, Ryan explains. ByteLight's equipment would capture the light strengths and patterns and transmit location information to phones. "Each bulb is a dumb beacon," he says.

The company is testing it at two undisclosed locations.

"There's a lot of experimentation," Bing's Nash says. "Maps will continue to be richer and more personalized."